ESTRO 2024 - Abstract Book

S3334

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Results:

Table 1 presents measured and calculated CAX offsets in the in-line and cross-line directions for the two detectors and all set-ups considered. For the in-line profile and in the parallel configuration, a systematic CAX offset of 0.51mm (mean value from 3 systems) was measured using the SF-3D but was not verified in the vertical set-up (-0.03mm), nor by the MD measurements (Table 1). According to MC-based results, this offset is reproduced (0.4mm) only if the DV effect is accounted for. The CAX offset is orientation dependent. Regarding the cross-line direction, the Lorentz force is responsible for the CAX offsets. According to the experimental results of Table 1 for the cross-line profile, the SF 3D's EPOM is shifted by 1mm as compared to MD. MC and experimental results agree within 0.5mm.

Table 1. Experimental and MC determination of CAX offsets in in-line and cross-line directions for the detectors studied, and for both set-ups (Figure 1).

Conclusion: